Auto Loan Calculator
Car loan payment from price, down payment, trade-in value and payoff, sales tax and fees, with total interest, the real cost of the car and a full payment schedule.
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About this toolWhat is the Auto Loan Calculator?
The Auto Loan Calculator works out a car payment the way a dealer's finance office does. Start with the negotiated price, subtract your cash down payment and the equity in your trade-in, add sales tax and fees if you are financing them, then amortize the result at your APR over the term in months.
It handles the details that change the answer: a trade-in you still owe money on (including negative equity), states that tax only the price after the trade-in credit versus those that tax the full price, and whether tax and registration are paid at signing or rolled into the loan.
Results show the monthly payment, the amount financed, the total interest, what is due at signing and the full cost of the car, plus a table comparing 36 to 84 month terms and a month-by-month schedule you can download.
- Trade-in value and payoff with negative equity handling
- Sales tax with or without the trade-in credit
- Tax and fees financed or paid at signing
- Total interest, total cost and amount due at signing
- Term comparison from 36 to 84 months and a downloadable schedule
How to use the Auto Loan Calculator
- Enter the negotiated vehicle price and your cash down payment.
- Enter the APR from your loan offer and the term in months, or tap one of the common terms.
- If you are trading in, enter the trade-in value and how much you still owe on it.
- Set the sales tax rate and fees, and choose whether the trade-in reduces the taxable price and whether tax and fees go into the loan.
- Read the payment, total interest and total cost, compare terms in the table, and open the schedule for month-by-month balances.
Worked examples
A typical deal with a trade-in
Input
Price 35,000; 5,000 down; trade-in 8,000 owing 3,000; 7% tax; 600 fees financed; 6.5% for 60 months
Output
Sales tax 1,890; amount financed 27,490; payment 537.87; total interest 4,782.40
Tax is charged on 27,000 (price minus the trade-in value), and the 5,000 of trade-in equity acts like extra cash down. The total cost of the car, including interest, tax and fees, is 42,272.40.
Stretching to 84 months
Input
Same deal over 84 months
Output
Payment 408.21; total interest 6,799.72
The payment falls by about 130 a month, but interest rises by more than 2,000 and you will owe money on the car for seven years.
Negative equity
Input
Same deal but 12,000 still owed on the 8,000 trade-in
Output
Amount financed 36,490; payment 713.97
The 4,000 shortfall on the old car is rolled into the new loan along with tax and fees, adding about 176 a month compared with the first example.
Background and insight
Car loans are simple-interest installment loans, so the maths is the same annuity formula as a mortgage: payment = P × r × (1 + r)^n / ((1 + r)^n − 1), with r the APR divided by 12 and n the number of months. What differs is the amount financed, which depends on how the deal is structured.
Trade-in equity is the trade's value minus any loan on it. Positive equity works like a down payment. Negative equity, where you owe more than the car is worth, is added to the new loan, so you keep paying for the old car with interest. In most US states the trade-in value is subtracted before sales tax is calculated, which can save hundreds; a few states, California among them, tax the full price. Check your state's motor vehicle department.
Longer terms lower the payment but raise total interest and keep you owing more than the car is worth for longer, because cars lose value fastest in the first years. The term table lets you see that trade-off directly.
Common use cases
Checking a dealer quote
Make sure the payment you are offered matches the price, rate and term on the paperwork.
Choosing a loan term
See exactly what a 72 or 84 month loan costs in extra interest.
Valuing a trade-in
Compare trading in against selling privately by changing the trade-in value and tax credit.
Setting a car budget
Work backwards from a payment you are comfortable with by adjusting the price.
Tips and limitations
- Negotiate the price first and the financing second; a low payment can hide a high price or a long term.
- Get a pre-approval from a bank or credit union so you have a rate to compare with the dealer's.
- Ask for the "out-the-door" price including all fees, then enter fees here so nothing is missed.
- Add-ons such as GAP cover or extended warranties increase the amount financed. Add them to fees to see their monthly and total cost.
- Sales tax rules vary by state and sometimes by county; treat the default 7% as a placeholder.
Frequently asked questions
How do I calculate a car loan payment?
Work out the amount financed (price − down payment − trade-in equity, plus tax and fees if financed), then apply payment = P × r × (1 + r)^n / ((1 + r)^n − 1), where r is the APR ÷ 12 and n the number of months. A 30,000 loan at 5% over 60 months is 566.14 a month.
Is sales tax calculated before or after the trade-in?
In most US states the trade-in value is deducted first, so you pay tax only on the difference. Some states, including California, tax the full purchase price. Use the toggle to match your state; in the default example the trade-in credit saves 560 of tax.
What happens if I owe more on my trade-in than it is worth?
The difference, called negative equity, is usually added to the new loan. You then pay interest on debt from the old car, and you start the new loan owing more than the new car is worth. If possible, pay the shortfall in cash or keep the old car longer.
Is a 72 or 84 month car loan a bad idea?
Not always, but it costs more. On a 27,490 loan at 6.5%, moving from 60 to 84 months lowers the payment by about 130 but adds over 2,000 of interest, and the slower paydown makes it more likely you owe more than the car is worth if you sell early.
Should I roll taxes and fees into my auto loan?
Paying them up front means borrowing less and paying less interest. Financing them is common and keeps cash free, but you pay interest on them for the whole term. Toggle Include tax and fees in the loan to see the difference for your deal.
Does a bigger down payment lower my car loan interest?
It lowers the amount you borrow, so total interest falls in proportion. Some lenders also offer better rates when you finance less of the car's value. Each 1,000 more down on a 60-month loan at 6.5% saves about 174 of interest and 19.57 a month.
Is there an in-depth guide to the Auto Loan Calculator?
Yes. “Car Loans, Leases and Paying Off Debt: The Numbers That Matter” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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